1. Field of the Invention
The present invention relates to a method for reducing proppant settling rates in fracturing fluids and to compositions and methods for using same.
More particularly, the present invention relates to a method for reducing proppant settling rates in fracturing fluids, where the method involves the step of injecting an amount of a gas below an amount sufficient to form a stable foam into the fracturing fluid, but sufficient to reduce a settling rate of proppants in the fracturing fluid including a proppant. The invention also relates to a composition including a fracturing fluid including proppants and an amount of a gas sufficient to reduce a settling rate of the proppant, yet insufficient to form a stable foam. The invention also relates to a method for fracturing a formation using a composition of this invention.
2. Description of the Related Art
Historically, the oil service industry deals with proppant settling by adjusting the viscosity of the fluid. Another method is to introduce gas or CO2 at high ratios to generate a foam. Foam viscosities are sufficient to suspend the proppant. Other than adjusting the viscosity or inducing a foam, no other methods or system to alter proppant settling rate has been introduced, except for CSI's introduction of proppants made of hollow glass beads.
In early November 2006 CSI Inc. introduced a method that alters the settling rate of proppants in a gelled fluid or frac fluid (fluid used in formation fracturing). The material is introduced to the fracturing fluid to alter the settling rate and is a light weight agglomerated material manufactured by 3M comprised of hollow glass beads, which are commonly used in cementing. These hollow glass beads have a density less than water and are common to cementing for lightening up the cement slurry.
Although several techniques are known for reducing proppant settling rates in fracturing fluids, sometimes referred to herein as frac fluids, there is still a need in the art for a straight forward general technique for reducing proppant settling rates in frac fluids.